This specification relates to quantum computing.
Quantum phase estimation is an important subroutine in many quantum computations. The eigenspectrum of all unitary operators are complex numbers with unit norm. The objective of quantum phase estimation can be to estimate the eigenphases of eigenvectors of a unitary operator. For example, for a quantum state |ψ that is an eigenstate of a unitary operator U|ψ=e−iϕ|ψ, an objective of quantum phase estimation is to estimate the value of ϕ.